1. Field of the Invention
This invention relates to a negative pressure dust collector, particularly to one capable of smoothly inflating a dust receiving bag.
2. Description of the Prior Art
As disclosed in Taiwan Patent No. M329475 shown in FIG. 1, a conventional dust collector includes a platform 1, an exhaust fan 2, a dust collection tank 3 and a filtration tank 4. The platform 1 is positioned in the intermediate portion of the dust collector, formed hollow, and provided with a suction tube 11 extended out of its circumferential wall and an opening 12 formed in its bottom to communicate with the suction tube 11. The exhaust fan 2 is provided with a motor 21 fixed next to the opening 12 of the platform 1, and a fan 22 positioned in the platform 1 and connected with the motor 21. The dust collection tank 3 is provided with an opening formed at the top for matching with the opening 12 of the platform 1 to communicate with the hollow interior of the platform 1, and a dust collection bag 31 placed in the interior. The filtration tank 4 is positioned right above the dust collection tank 3, with an opening formed downward to match with the opening 12 of the platform 1 to communicate with the platform 1. A suction tube 42 has its one end connected with an outer wall of the filtration tank 4 and the other end extended inside the interior of the platform 4. The main improvement of the conventional dust collector is that a connecting tube 41 is linked between the wall of the dust collection tank 3 and that of the suction tube 42. In using, when the exhaust fan 2 is turned on, it starts forcing the suction tube 11 and the connecting tube 41 sucked so that the air inside the dust collection tank 3 is to be sucked away to keep the dust collection bag 31 closely attached on the inner wall of the dust collection tank 3. However, as the opening of the connecting tube 41 is perpendicular to the flowing direction of the air sucked, suction in the connecting tube 41 cannot so effectively be achieved that the dust collection bag 31 may be reduced in sucking force.